Central sleep apnea (CSA) is characterized by intermittent episodes of decreased ventilation due to lack of drive to breathe while asleep. It is due to an abnormal carbon dioxide control of ventilation which may be due to blunted or enhanced ventilatory response to carbon dioxide. An increased CO2 sensitivity, an important factor in the development of central sleep apnea, precipitates it when associated with unstable breathing, i.e., high loop gain. The combination of speed of feedback gain, plant gain, and controller gain leads to high loop gain. We hereby report a case of central sleep apnea precipitated after coronary artery bypass grafting (CABG) performed via midline sternotomy. Factors responsible for sleep apnea in this case were cardiac failure, postsurgery low cardiac output syndrome, and decreased thoracic cage movement due to sternotomy. Normally these postsurgical cases resolve on their own, but our patient had very severe symptoms and hence he reported.
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